(Reprinted May 1931)
FERTILIZER EXPERIMENTS
WITH CORN
By
J. T. WILLIAMSON, W. H. APPLETON
AND H. B. HELMS
AGRICULTURAL EXPERIMENT STATION
OF THE
ALABAMA POLYTECHNIC INSTITUTE
M. J. FUNCHESS, Director
AUBURN
CIRCULAR 52 DECEMBER 1927
Fertilizer Experiments With Corn
By
J. T. Williamson, W. H. Appleton, and H. B. Helms
T HE return received from the use of commercial fertilizer
upon any crop is dependent on a number of factors. The
more important of these factors are the kind of fertilizer,
the fertility of the soil, the ratio of the different fertilizer con-
stituents to each other, and the method and time of application
of the fertilizer to the crop. For the solution of some of our ferti-
lizer problems it is essential that the above factors be recognized
and experiments planned to study as far as possible only one
factor at a time. With this principle in mind, experiments were
outlined for the purpose of studying some of the problems relat-
ing to the fertilization of corn.
Three of the most important problems relating to the use of
fertilizer for corn in Alabama are:
(a) The importance of nitrogen, phosphorus, and potash
on the soils of the different soil divisions of the State.
(b) The relative value of cottonseed meal and nitrate of
soda as sources of nitrogen.
(c) The best time for applying nitrate of soda to the crop.
The present study was undertaken in an effort to secure data
that would solve these problems. The results of the investiga-
tion are given in this publication.
Methods.-All of the experiments reported were conducted
cooperatively with farmers in the several counties of Alabama.
In each case a representative from the experiment station select-
ed the land and measured the plots. Fertilizers for each plot
and instructions concerning their application were sent from the
experiment station to each cooperator. In the case of the ex-
periments on the time of application of nitrate to corn, all ferti-
lizers were applied by the representative of the experiment sta-
tion. Each experiment was inspected one or more times during
the growing season. All fertilizers except nitrate of soda were
applied in the drill before planting. The nitrate of soda in
the experiments on the relative value of nitrogen, phosphorus,
and potash was applied when the plants were two to three feet
high.
EXPERIMENTS ON THE RELATIVE VALUE OF
NITROGEN, PHOSPHORUS, AND POTASH
Series 1
During the period 1911 to 1921 a large number of corn fer-
tilizer experiments were conducted on the different soil divisions
of the State but the results of most of these experiments were
lost by fire in 1920. However, the results of 56 of these tests
were saved and are reported in Tables 1 and 2, pages 8, 9, and
10.
Table 1 gives the average yield of corn, the increased yield
due to fertilization, and the average profit from the use of fer-
tilizers as determined by the experiments on the several soil
divisions of the State. The increase in yield due to fertilizer on
a given plot is calculated by subtracting the average yield of
the unfertilized plots from the yield of the plot receiving fertiliz-
er.
In calculating the profit from the use of fertilizer the follow-
ing prices for fertilizer and for corn have been used throughout
this bulletin.
Acid phosphate ......-------------- $18.00 per ton
Nitrate of soda ---..-------------.- 60.00 per ton
Cottonseed meal -------------------- 38.00 per ton
Kainit -----------.---------------------- 14.00 per ton
Muriate of potash .....-------------. 50.00 per ton
Corn---------------------------------1.00 per bushel
With the exception of the price of kainit and muriate, these
prices are believed to be near the average for these fertilizing
materials and for corn from 1911 to 1927. During the war
period, unmixed kainit and muriate were practically unobtain-
able by farmers.
The price used for corn is an arbitrary one since the price
farmers receive is very different from the price paid for corn
after it has been shucked, shelled, graded, stored, and handled
by elevators, railroads, and merchants. The profit calculations
are on the basis of corn standing ready to harvest in the field.
No charge has been made for hauling and applying the fertiliz-
ers, interest, or any other expenses incurred from the use of
fertilizers.
The results in Table 1 show that there has been no consist-
ent profit from the use of phosphate, potash, or cottonseed meal
singly or in combinations. The most consistently profitable fer-
tilizer was the complete fertilizer containing nitrate of soda as
the source of nitrogen. This, however, failed to give a profit on
the soils of the Greenville-Orangeburg group. A comparison of
the profit obtained from the fertilizer on Plots 10 and 12 shows
that in all cases the greatest profit was obtained on Plot 12 indi-
cating the decided advantage of using nitrate of soda as a source
of nitrogen instead of cottonseed meal.
In order to evaluate better the influences of the various fer-
tilizer constituents, the data in Table 2 have been calculated.
Table 2 gives the increase per acre and the return per dollar
invested for the various fertilizer materials when used in a
complete fertilizer. The method of obtaining the yields of fer-
tilizer materials when used in a complete fertilizer is as follows:
The increase due to acid phosphate is obtained by sub-
tracting the yield of Plot 6 from that of Plot 9; the value
of 100 pounds of kainit is obtained by subtracting the
yield of Plot 5 from that of Plot 10; the value of cotton-
seed meal is obtained by subtracting the yield of Plot 8
from the yield of Plot 9. To find the value of nitrate of
soda, the yield of Plot 10 is subtracted from that of Plot
12, the figure thus obtained is added to or substracted
from the value of cottonseed meal which was obtained as
explained above.
These data show that on the Decatur and Colbert soils, acid
phosphate, kainit, and cottonseed meal gave no profit, the re-
turn per dollar invested in each case being less than $1.00. Ni-
trate of soda in a complete fertilizer gave a small net return on
the investment. On the DeKalb soils acid phosphate and kainit
gave a small return on the investment. Cottonseed meal, on the
other hand, returned only 74 cents for each dollar invested. Ni-
trate of soda gave a larger net return than any other fertilizer
material used on the DeKalb soils. The results obtained on the
Cecil and the Louisa soils of the Piedmont division are similar to
those obtained on the DeKalb soils in that there is a profit from
the use of acid phosphate and kainit in a complete fertilizer.
Likewise, the greatest profit was obtained from the use of ni-
trate of soda.
The Black Belt soils-Houston, Sumter, and Oktibbeha
were the only soils on which cottonseed meal returned a profit.
Acid phosphate also returned a profit on these soils while the
results obtained from kainit were conflicting. One hundred
pounds of kainit apparently gave a large profit while 200
pounds was unprofitable.
There are two groups of soils in the Coastal Plain division
the Norfolk-Ruston group and the Greenville-Orangeburg group.
None of these soils gave a pofit from the use of phosphate, kain-
it, or cottonseed meal. The soils in the Norfolk-Ruston group
returned a good profit from the use of nitrate of soda in the
complete fertilizer, while the soils of the Greenville-Orangeburg
group showed only a very small profit from the use of nitrate.
Series 2
During the years 1925-1926 additional experiments were
conducted to determine the value of phosphate, potash, and ni-
trogen for corn. In these experiments 100, 200, and 300 pounds
of nitrate of soda were used with and without the addition of
200 pounds of acid phosphate and 25 pounds of muriate of pot-
ash. The results of these experiments are given in Table 3, page
11.
The figures in Table 3 show that on the soils of the Norfolk-
Ruston group phosphorus and potash produced a slight increase
in yield when used with 100 or 200 pounds of nitrate of soda.
The increase was not great enough to be considered profitable.
When used with 300 pounds nitrate of soda, however, the phos-
5
phate and potash gave a profit of $2.05 
per acre. On the De-
kalb soils phosphate and potash alone 
and nitrate of soda alone
failed to give a profit. The use of a complete 
fertilizer, how-
ever, was slightly profitable but in no 
instance was the profit
nearly so great as was obtained on 
the Norfolk-Ruston soils.
The Hagerstown and Decatur soils differ from 
the other
soils used in these experiments in that they 
are considerably
more fertile. This is indicated by a 
comparison of the yields
obtained on the check plots. As might be expected, 
the return
from the use of fertilizer on land producing 
an average of 31
bushels of corn per acre was small. On 
these soils the greatest
profit was secured when phosphate and 
potash were used with
200 pounds of nitrate of soda per 
acre. The differences, how-
ever, were so small that any conclusions 
drawn are subject to
question.
EXPERIMENTS ON THE TIME OF APPLYING
NITRATE
Fourteen experiments were conducted in different parts 
of
the State in the years 1923-1924 to determine the effect 
of time
of application of nitrate on the yield of corn. The general pro-
cedure in each experiment was to fertilize 12 one-twentieth-acre
plots with the same amounts of acid phosphate and muriate of
potash, and all except the check plots with equal amounts of ni-
trate of soda. Acid phosphate and muriate of potash were used
at the rate of 200 pounds and 25 pounds per acre, respectively.
These materials were applied in the drill just before planting.
Nitrate of soda at the rate of 200 pounds per acre was applied as
indicated in Table 4, page 12.
On the light or sandy soils excepting the plot receiving 
the
broadcast application of nitrate-the increase due to the appli-
cation of 200 pounds of nitrate varied from 12.9 bushels to 16.2
bushels. The highest yield was secured from the plot receiving
all of the nitrate 35 days after planting. It is apparent, how-
ever, that the time of application of nitrate does not influence
the corn yield as much as the yield of cotton.
The experiments on heavy soils-mostly silt loams and clay
loams-show about the same order of results as the experiments
on the sandy soils. The small differences obtained as a result
of applying nitrate at different times are probably not very sig-
nificant. The results, however, show that there is little or no
advantage in making two applications of nitrate to corn. Ap-
parently the best practice would be to make one application of
nitrate 30 or 40 days after planting.
Discussion.-The foregoing results show that when used as
direct fertilizer to corn no material profits were secured from
the use of phosphate, kainit, or cottonseed meal on the soils 
of
the Limestone Valleys and the Coastal Plains. While there were
6
some cases where these materials paid their cost and some in-
terest on the investment on the soils of the Appalachian Plat-
eau, Piedmont Plateau, and Black Belt, the small margin of
profits on these soils usually made their use of questionable
value.
There is nothing in these results, however, which indicates
that the quantity of acid phosphate and potash per acre or per
farm should be reduced. The data presented show only the
value of these materials when applied directly to corn. Cotton
and some other crops that are commonly used in rotation with
corn on the soils represented by these experiments respond quite
readily to acid phosphate and potash. The residual effect of
these materials when applied to crops other than corn in the
rotation is often sufficient to take the place of the direct appli-
cation to corn. No doubt a complete history of the soils on
which these experiments were conducted would reveal that in
many cases considerable phosphate and potash had been ap-
plied to the preceding crops.
In almost all the experiments reported, the use of nitrogen in
the form of cottonseed meal or nitrate of soda gave larger in-
creases than did the use of phosphate or potash. In a number
of the experiments the use of nitrate of soda was very profitable.
In general the results indicate that corn should not receive phos-
phate and potash but should be fertilized with nitrate of soda.
While nitrate of soda was the only source of inorganic nitro-
gen used in these experiments, it is probable that similar results
would have been secured with other readily available basic ni-
trogenous fertilizers. Acid-forming nitrogenous fertilizers prob-
ably would have given similar results in these short-time tests.
Their regular use is not to be recommended, however, unless
lime is added to correct the resulting acidity.
A comparison with the results obtained on Plots 10 and 12
of Series 1 shows that a given amount of nitrogen in nitrate of
soda produced larger increases than an equivalent amount of
nitrogen in cottonseed meal. Not only is the nitrogen in nitrate
of soda more efficient for the production of corn, but it is usually
less expensive per unit than is the nitrogen in cottonseed meal.
The results reported in this bulletin on the time of apply-
ing nitrate of soda to corn agree with the results obtained and
reported in Alabama Experiment Station Bulletin No. 210. They
show that nitrate of soda should be applied to corn five or six
weeks after planting. They also show that there is little or no
advantage in making two applications of nitrate of soda instead
of one.
The losses, or very small profits, due to the use of fertilizers
to corn as compared with the profit usually secured from the ap-
plications of fertilizer to other crops can be explained by noting
that-with the possible exception of oats-the unit value of corn
is lower than the unit value of any other common farm crop.
The value of a pound of corn to the farmer is usually between 1
and 2 cents in comparison with the value of 6 to 8 cents for a
pound of seed cotton.
The increases in pounds of corn per acre have been slightly
larger on the average than the increase in pounds of seed cotton
obtained by this station on these soil regions from the use of the
same kinds and quantity of fertilizing materials. However, the
profit due to fertilizers on corn is usually small while on cotton
good fertilization is nearly always profitable. These considera-
tions lead to the conclusion that the best farm practice would
be to apply all of the phosphate and potash to cotton. Corn
following cotton that has been well fertilized should not receive
phosphate and potash but should be fertilized with nitrate of
soda.
SUMMARY
A. Fifty-six corn fertilizer experiments conducted from 1911 to
1921 show:
(1) That fertilization of corn with acid phosphate or
kainit was unprofitable except on soils of the Appa-
lachian and Piedmont Plateaus.
(2) That cottonseed meal seldom returned a profit but
that nitrate of soda gave a profit on all the soils
studied.
(3) The profit from nitrate of soda was largest on soils
of the Appalachian and Piedmont Plateaus and small-
est on the Greenville-Orangeburg soils of the Coastal
Plain.
B. Eleven experiments were conducted in 1925 and 1926 on the
value of phosphate and potash for corn with varying amounts
of nitrate of soda. The results indicate that corn seldom
returns a profit from the use of phosphate and potash.
C. The results of experiments on time of applying nitrate of
soda to corn show that the best time of application is about
six weeks after planting. There is no advantage in applying
the nitrate in two applications instead of one.
Table 1.-Results of Fertilizer Experiments with Corn on the Principal Soil Types of Alabama
Amt. 
Decatur and Colbert Soils* 
DeKalb Soils** Cecil and Louisa 
Soils***
Plot ferti- Kind of Average Increase Average Average 
Increase Average Average Increase Average
No. lizer Fertilizer yield over un- profit per yield over un- profit per yield over un- profit per
per corn per fertilized 
acre from corn per fertilized acre from corn per fertilized 
acre from
acre acre plots fertilizers acrers
Lbs. Bus. Bus. Dollars Bus. 
Bus. Dollars Bus. Bus. Dollars
1 200 Cottonseed meal 26.8 3.1 -0.70 13.3 
2.0 -1.80 19.4 1.6 -2.20
2 240 Acid phosphate 26.1 2.4 0.24 
14.7 3.4 1.24 18.1 0.3 -1.86
3 --- No fertilizer 23.3 -
10.5 - 16.6 -
4 200 Kainit 24.3 0.6 -0.80 
10.9 -0.4 -1.80 16.8 -1.0 -2.40
S200 Cottonseed 
meal
5 1240 Acid phosphate 29.5 5.8 
-0.16 13.7 2.4 -3.56 20.0 2.2 
-3.76
$200 Cottonseed meal
6 1200 Kainit 29.1 
5.4 0.20 14.6 3.3 -1.90 18.5 
0.7 -4.50
7 ___ No fertilizer 23.8 -
11.7 - 18.1 -
$240 Acid phosphate
8 1200 Kainit 27.9 4.2 
0.64 14.6 3.3 -0.26 18.9 1.1 -2.46
200 Cottonseed meal
9 240 Acid phosphate 30.3 6.6 -0.76 17.4 
6.1 -1.26 22.2 4.4 -2.96
200 Kainit
200 Cottonseed meal
10 240 Acid phosphate 29.7 6.0 
-0.66 14.3 3.0 -3.66 22.5 4.7 -1.96
L100 Kainit
11 __ No fertilizer 23.9 -
11.8 - 18.6 -
100 Nitrate of soda
12 240 Acid phosphate 30.9 7.2 1.34 
21.1 9.8 3.94 27.6 9.8 3.94
[100 Kainit
* 11 experiments, ** 4 experiments, *** 5 experiments.
Table 1 (continued).-Results of Fertilizer Experiments with Corn on the Principal Soil Types of Alabama
Kind of
Fertilizer
Plot
No.
14 experiments,
Houston, Sumter, and
Oktibbeha Soils*
Average Increase Average
yield over un- profit per
corn per fertilized acre from
acre plots fertilizers
Bus. Bus. Dollars
Amt.
f erti-
lizer
per
acre
Lbs.
200
240
200
S200
2240
S200
2200524
2200
(200
X240
L200
(200
X240
[100
rioo
1 240
1100
8.8
3.1
0.8
8.9
5.4
2.6
9.5
9.1
5.00
0.94
-0.60
2.94
0.20
-0.96
2.14
2.44
, 18 experiments.
Norfolk Soil Group*
Average Increase Average
yield over un- profit per
corn per fertilized acre from
acre plots fertilizers
Bus. Bus. Dollars
21.8
18.4
17.5
18.0
22.7
21.4
16.7
18.0
21.5
20.7
16.5
23.7
4.9
1.5
1.1
5.8
4.5
1.1
4.6
3.8
6.8
1.10
-0.66
-0.30
-0.16
-0.70
-2.46
-2.76
-2.86
1
2
3
4
5
6
7
8
9
10
11
12
Greenville Soil Group***
Average Increase Average
yield over un- profit per
corn per fertilized acre from
acre plots fertilizers
Bus. Bus. Dollars
19.1
17.0
16.3
16.8
19.2
18.6
17.2
17.9
19.5
19.8
16.2
21.4
2.5
0.4
0.2
2.6
2.0
1.3
2.9
3.2
4.8
-1.76
-1.20
-3.36
-3.20
-2.26
-4.46
-3.46
-1.06
31.8
26.1
22.2
23.8
31.9
28.4
23.6
25.6
32.5
32.1
23.3
Cottonseed meal
Acid phosphate
No fertilizer
Kainit
Cottonseed meal
Acid phosphate
Cottonseed meal
Kainit
No fertilizer
Acid phosphate
Kainit
Cottonseed meal
Acid phosphate
Kainit
Cottonseed meal
Acid phosphate
Kainit
No fertilizer
Nitrate of soda
Acid phosphate
Kainit
0.94
ii I I I~ I I I II
4 epeimets
Table 2.-Average Return from the Use of Acid Phosphate, Kainit, Cottonseed Meal, and Nitrate of Soda in a Com-
plete Fertilizer for Corn
Acid phosphate Kainit Kainit Cottonseed meal Nitrate of soda
(240 lbs.) (200 lbs.) (100 lbs.) (200 lbs.) (100 lbs.)
Soil Types
Bus. Per Bus. Per Bus. Per Bus. Per Bus. Per
per dollar per dollar per dollar per dollar per dollar
acre invested acre invested acre invested acre invested acre invested
Bus. Dollars Bus. Dollars Bus. Dollars Bus. Dollars Bus. Dollars
Decatur
Colbert ______-________-___ -1.2 0.56 0.8 0.57 0.2 0.29 2.4 0.63 3.6 1.20
DeKalb ____------ ---- _____ 2.8 1.29 3.7 2.64 0.6 0.86 2.8 0.74 9.6 3.20
Cecil
Louisa--- -------- 3.7 1.71 2.2 1.57 2.5 3.57 3.3 0.87 8.4 2.80
Houston, Sumter
Oktibbeha--------- 4.1 1.89 0.6 0.43 0.2 4.00 6.9 1.82 - -
Norfolk
Ruston- __------ --- 0.1 0.04 -1.2 -1.86 -2.0 -3.86 3.5 0.92 6.5 2.17
Greenville
Orangeburg 0.9 0.42 0.3 0.21 0.6 0.86 1.6 0.42 3.2 1.07
10
Table 3.-The Relative Value of Nitrate of Soda and of Acid Phosphate and Muriate of Potash for Corn on Different
Soil Types
Norfolk and Ruston
(4 experiments)
Plot
No.
Increase
per acre
Bus.
Fertilizer
Treatment
0
P K
N
N P K
0
2N
2N 1P 1K
3N
3N 1P 1K
0
Profit
per acre
Dollars
Yield
per acre
Bus.
13.59
17.75
24.53
25.86
15.73
32.06
34.13
33.99
38.46
16.13
DeKalb
(3 experiments)
Yield
per acre
Bus.
19.86
20.67
22.44
26.09
19.42
23.77
30.09
26.00
32.13
20.66
Increase
per acre
Profit
per acre
Hagerstown and Decatur
(4 experiments)
Yield
per acre
Increase
per acre
Profit
per acre
-1 1 - I- -_
Bus.
0.69
2.46
6.11
3.79
10.11
6.02
12.15
Dollars
-1.73
-0.54
0.69
-2.21
1.69
-2.98
0.73
Bus.
30.79
35.66
34.99
35.99
31.26
37.99
42.53
40.93
42.00
31.99
Bus.
4.32
3.65
4.65
6.65
11.19
9.59
10.66
2.60
9.38
10.71
16.91
18.98
18.84
23.31
1
2
3
4
5
6
7
8
9
10
0.18
6.38
5.29
10.91
10.56
9.84
11.89
Dollars
1.90
0.65
-0.77
0.65
2.77
0.59
-0.76
' 1 1 1 -- 1.4
N-100 lbs. nitrate of soda, P-200 lbs. acid phosphate, K-25 lbs. muriate of potash.
11
- -_
12
Table 4.-Average Results Obtained from Applying Nitrate of Soda
to Corn at Different Stages of Growth
Am. Nitrate Fertilization 
( Sandy soils Heavy 
soils
Plot_____per____ 
(8_ experiments) 
(6 experiments)
No. acre Tieoaplctn Yield Increase Yield Increase
Timeof apliction per acre per acre per acre per acre
Lbs.
0
200
200
0
200
200
100
100
0
100
100
100
100
67
67
67
1
2
3
4
5
6
7
8
9
10
11
12
At planting (Bdc.)
At planting (Drill)
35
65
35
65
days after
days after
days after
days af ter
planting
planting
planting
planting
At planting
35 days after planting
At planting
65 days after planting
At planting
35 days after planting
65 days after planting
Bus
17.8
28.0
31.3
16.8
32.9
30.1
31.8
15.4
29.6
30.3
31.0
16.9
Bus.
11.3
14.6
16.2
13.4
15.1
12.9
13.6
14.3
14.8
25.0
28.0
17.6
28.6
27.9
29.8
16.0
27.2
28.1
25.6
13.2
Bus.
9.6
12.6
13.2
12.5
14.4
11.8
12.7
10.2
0
v